Tape recorder

ABSTRACT

The pointer which is movable along a scale on the deck of a tape recorder to indicate that length of tape which is available for recordal or reproduction of sound has a follower which tracks the thread of a spindle driven by the takeup reel at a speed which varies as a function of changes in diameter of tape which is convoluted on the core of the takeup reel. The graduations of the scale are equidistant from each other; therefore, the pitch of the thread on the spindle varies as a function of changes in rotational speed of the takeup reel when the tape is transported at a constant speed.

United States Patent 187,193,194,197, 201,202,205, 206; 74/567, 569;33/127; 2 74/1 1 C, 11 D, 11 E,4C,4 D; 116/135 11111119111101 111111111111111111111111111111111111111ll11111111l1l1l11l1111111111111l1111111111111111111111111111111111111111111l111l1il111ll1111111111111l11ll1l11lll111111111l111111l1l1111l1l111l1111111l11111111111111l111ll11111111111111111111111111l11l11111111111111111111111111111111111111Primary Examiner-Stanley N. Gilreath Assistant ExaminerWerner H.Schroeder Attorney-Michael S. Striker ABSTRACT: The pointer which ismovable along a scale on the deck of a tape recorder to indicate thatlength of tape which is available for recordal or reproduction of soundhas a follower which tracks the thread of a. spindle driven by thetakeup reel at a speed which varies as a function of changes in diameterof tape which is convoluted on the core ofthe takeup reel. Thegraduations of the scale are equidistant from each other; therefore, thepitch of the thread on the spindle varies as a function of changes inrotational speed of the takeup reel when the tape is transported at aconstant speed.

PATENIEU SEP28 l9?! llnventor: HANSWERNE R PIEPLOW w u 1. M "kw-Al'lorney TAPE RECORDER BACKGROUND OF THE INVENTION The presentinvention relates to sound recording and/or reproducing apparatus(hereinafter called tape recorders), and more particularly toimprovements in a mechanism which moves the pointer along a scaleserving to indicate the length of tape which is convoluted on the supplyor takeup reel.

A tape recorder comprises a transporting mechanism which moves the tapelengthwise at a constant speed whereby the supply and takeup reelsrotate at a speed which varies as a function of the diameter of tapewhich is convoluted on their cores. For example, if the tape is beingwithdrawn from the supply reel, the diameter of tape on the core of thesupply reel decreases and the diameter of tape on the core of the takeupreel increases. Consequently, and assuming that the tape is transportedat a constant speed, the takeup reel must be rotated at a decreasingspeed and the speed of the supply reel increases proportionally with theincrease in diameter of convoluted tape on the core of the takeup reel.

Many tape recorders are further provided with indicating means tofacilitate continuous determination of that length of tape which isalready convoluted on the core of the takeup reel (or which is stillstored on the core of the supply reel). As a rule, such indicating meanscomprises an elongated scale whose graduations indicate differentlengths of tape or different units of time, a pointer which is movablealong the scale, and a spindle which is driven by one of the reels andwhose thread is tracked by a follower on the pointer so that the pointermoves along the scale in response to rotation of the spindle. The pitchof the thread on the spindle (namely, the distance, measured parallel tothe spindle axis, between corresponding points on adjacent threads inthe same axial plane) is constant; therefore, the distance betweensuccessive graduations must vary as a function of changes in rotationalspeed of the reel which drives the spindle. If the spindle is driven bythe takeup reel, the distance between successive graduations of thescale increases in the direction in which the pointer travels when thetakeup reel is rotated to collect the tape. Thus, and assuming that thegraduations of the scale represent units of time, the distance betweensuccessive graduations at one end of the scale is but a small fractionof the distance between graduations at the other end of the scale. Thesame applies if the graduations indicate unit lengths of tape. Suchnonuniform distribution of graduations is a source of constantirritation to the user of the tape recorder. The problems are similar ifthe takeup reel drives a digital counter because the wheels of thecounter rotate much faster when the takeup reel begins to collect thetape and very slowly when the trailing portion of the tape is about tobe collected by the core of the takeup reel.

SUMMARY OF THE INVENTION An object of the invention is to provide a taperecorder with novel and improved indicating means wherein the pointercovers identical distances per unit of time despite the fact that thedrive for the pointer receives motion from one of the reels, i.e., froma part whose speed changes continuously while the tape is caused to moveat a constant speed.

Another object of the invention is to provide a novel and improvedspindle for use in such indicating means.

A further object of the invention is to provide indicating means whereinthe graduations of the scale are equidistant from each other despite thefact that the pointer is driven by means which receives motion from oneof the reels.

The improved tape recorder comprises a support which may constitute adeck for two discrete reels or the housing of a cassette, a pair ofreels rotatably mounted on the support, a length of magnetic tape havingends connected with the cores of the two reels, transporting means foradvancing the tape lengthwise at a predetermined speed and for rotatingone of the reels so that the respective core collects the tape thereonand the speed of the reels varies as a function of changes in ism withthe scale, follower means provided on the pointer and tracking thethread of the spindle so that the pointer moves in response to rotationof the spindle, and means (preferably including a belt drive and a wormdrive) for rotating the spindle in response to and in synchronism withrotation of one of the cores. In accordance with a feature of theinvention, the pitch of the thread on the spindle varies from one endtoward the other end of the spindle in such a way that the pointer ismoved through identical distances per each unit of time in response torotation of the one core while the tape is advanced at the predeterminedspeed. Thus, by utilizing a spindle whereon the pitch of the threadvaries. as a function of changes in rotational speed of the reels, thepointer can cover identical distances during successive unit lengths oftime so that the reading of the scale is more convenient because all ofthe graduations on the scale can be placed at the same distance fromeach other regardless of whether such graduations indicate units of timeor unit lengths of tape.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved tape recorder itself, however, both as to its construction andits mode of operation, together with additional features and advantagesthereof, will be best understood upon perusal of the following detaileddescription of certain specific embodiments with reference to theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a fragmentaryschematic plan view of a tape recorder which embodies the invention,certain parts of the tape recorder being shown in section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing illustrates aportion of a tape recorder including a deck 1 which constitutes asupport for a takeup reel 3 having a core 3a and a supply reel 4 whosecore is shown at 4a. The trailing and leading ends of the magnetic tapeT are respectively connected with the cores 4a, 3a and the tape istrained over guide rolls 1a, lb. The recording, erasing and reproducingheads are not shown. The transporting mechanism for moving the tape Tlengthwise at a constant speed comprises a driven wheel 15 which ismovable toward and away from an idler wheel 16 to move the tapelengthwise when it assumes the illustrated position. The transportingmechanism further includes a clutch element 17 which drives the core 30of the takeup reel 3 when the tape is transported in the directionindicated by arrow 18. During such lengthwise movement of the tape T ata constant speed, the rotational speed of the reel 3 and core 3adecreases proportionally with an increase in diameter of tape which isconvoluted on the core 3a. The rotational speed of the reel 4 (whichthen rotates in response to pull exerted by the tape T) increases at thesame rate at which the rpm. of the core 3a decreases. The numerals 2, 2arespectively denote the shafts for the cores 3a, 40. Each of the reelscan be slipped onto and removed from the respective shaft.

The indicating means which enables the user to determine the length oftape on the core 3a and/or 4a includes an elongated scale 11 havingequidistant graduations 12 which indicate units of time (for example,in. minutes) or unit lengths of tape (for example, in meters or feet).

A pointer or index 10 is mounted for travel along the scale 11 and thedrive means for moving the pointer includes an elongated spindle 8 whoseend portions I3, 14 are joumaled in bearings 19, 20 provided on thedeck 1. The spindle 8 is parallel with the scale ll and its externalthread 8a is tracked by a follower a of the pointer 10. The latter isheld against rotation about the spindle 8 by an elongated guide 21. Themechanism which drives the spindle 8 comprises a first pulley 6a on theshaft 2 or core 3a, a second pulley 6 which is mounted on a worm shaft7, an endless belt or rope S which is trained over the pulleys 6, 6a anddrives the pulley 6 at a speed which is less than but proportional tothe speed of pulley 6a and core 30, and a worm wheel 9 which is rigidwith the spindle 8 and meshes with the worm on the shaft 7. Thus, thespeed of the spindle 8 varies with the speed of the core 3a.

in accordance with a feature of the invention, the pitch of the thread80 on the spindle 8 varies from the end portion 13 toward the endportion 14 in such a way that, when the tape T is advanced at a constantspeed and the reel 3 is rotated at a decreasing speed, the pointer 10advances through identical distances per successive units of time. Thus,the pitch of the thread 80 increases from the end portion 13 toward theend portion 14 at the same rate at which the r.p.m. of the core 3adecreases when the reel 3 rotates in response to transport of tape T ata constant speed (arrow 18).

The spindle 8 is preferably made by injection molding from suitablesynthetic plastic material. The variations in the pitch of the thread 8acan be determined by resorting to the equawherein s is the variation inpitch, s is the initial value of the pitch at the end portion 13, v isthe speed of tape T, t is the interval of time during which the tape istransported, d is the thickness of tape, and r is the radius of the core3a. It will be seen that the rate at which the pitch s varies isreciprocal to the rate at which the r.p.m. of the core 3a changes whilethe tape T advances at a constant speed.

When the pointer 10 is located, for example, halfway between the ends ofthe thread 8a, the user of the tape recorder knows that one-half of thetape T is still available for recordal or reproduction of sound.

it is clear that the support 1 can constitute the housing of a cassettefor magnetic tape and that the parts 8, 10, 11 are then mounted in or onthe housing of the cassette.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. In a tape recorder, a combination comprising a support; a pair ofreels rotatably mounted on said support and each having a core; a lengthof magnetic tape having end portions connected with said cores;transporting means for advancing the tape at a predetermined speed andfor rotating one of said reels so that the respective core collects thetape thereon and the speed of said reels varies as a function .ofchanges in diameter of convoluted tape on said cores; a fixed scalehaving a row of equidistant graduations; a pointer movable along saidscale and including follower means; and drive means for moving saidpointer along said scale, including aspindle rotatably mounted on saidsupport and extending in parallelism with said scale, said spindlehaving an external thread tracked by said follower means so that thelatter moves the pointer in response to rotation of said spindle, andmeans for rotating said spindle in response to and in synchronism withrotation of one of said cores, the pitch of said thread varying from oneend toward the other end of said spindle so that said pointer is movedthrough identical distances per each unit of time in response torotation of said one core while the tape is advanced at saidpredetermined speed.

2. A combination as defined in claim 1, wherein said support is the deckof the ta e recorder.

3. A combination as efined in claim 1, wherein the rate at which thepitch of said thread varies is the reciprocal of the rate at which thespeed of said one core varies while the tape is transported at saidpredetermined speed.

4. A combination as defined in claim 1, wherein the pitch s of saidthread varies in accordance with the equation wherein so is the pitch atsaid one end of the spindle, v is the speed of the tape, t is the lengthof the interval during which the tape is transported, d is the thicknessof tape, and r is the radius of said one core.

5. A combination as defined in claim 1, wherein said spindle consists ofsynthetic plastic material.

6. A combination as defined in claim 1, wherein said means for rotatingsaid spindle comprises a worm drive.

7. A combination as defined in claim 1, wherein said means for rotatingsaid spindle comprises a belt drive.

8. A combination as defined in claim 1, wherein said graduationsindicate various lengths of the tape.

9. A combination as defined in claim 1, wherein said graduationsindicate units of time.

10. A combination as defined in claim 1, wherein said reels include asupply reel and a takeup reel and said one core is the core of saidtakeup reel.

1. In a tape recorder, a combination comprising a support; a pair ofreels rotatably mounted on said support and each having a core; a lengthof magnetic tape having end portions connected with said cores;transporting means for advancing the tape at a predetermined speed andfor rotating one of said reels so that the respective core collects thetape thereon and the speed of said reels varies as a function of changesin diameter of convoluted tape on said cores; a fixed scale having a rowof equidistant graduations; a pointer movable along said scale andincluding follower means; and drive means for moving said pointer alongsaid scale, including a spindle rotatably mounted on said support andextending in parallelism with said scale, said spindle having anexternal thread tracked by said follower means so that the latter movesthe pointer in response to rotation of said spindle, and means forrotating said spindle in response to and in synchronism with rotation ofone of said cores, the pitch of said thread varying from one end towardthe other end of said spindle so that said pointer is moved throughidentical distances per each unit of time in response to rotation ofsaid one core while the tape is advanced at said predetermined speed. 2.A combination as defined in claim 1, wherein said support is the deck ofthe tape recorder.
 3. A combination as defined in claim 1, wherein therate at which the pitch of said thread varies is the reciprocal of therate at which the speed of said one core varies while the tape istransported at said predetermined speed.
 4. A combination as defined inclaim 1, wherein the pitch s of said thread varies in accordance withthe equation wherein so is the pitch at said one end of the spindle, vis the speed of the tape, t is the length of the interval during whichthe tape is transported, d is the thickness of tape, and r is the radiusof said one core.
 5. A combination as defined in claim 1, wherein saidspindle consists of synthetic plastic material.
 6. A combination asdefined in claim 1, wherein said means for rotating said spindlecomprises a worm drive.
 7. A combination as defined in claim 1, whereinsaid means for rotating said spindle comprises a belt drive.
 8. Acombination as defined in claim 1, wherein said graduations indicatevarious lengths of the tape.
 9. A combination as defined in claim 1,wherein said graduations indicate units of time.
 10. A combination asdefined in claim 1, wherein said reels include a supply reel and atakeup reel and said one core is the core of said takeup reel.